1. Field of the Invention
The invention relates generally to a ship's door or hatch arrangement with a frame and a door leaf and, more particularly, to a door which can be mechanically locked to the frame in which it is removably mounted.
2. Description of the Prior Art
Already known are watertight doors and hatches which are provided with a locking mechanism such as separate sash locks as well as sash locks which are actuated centrally by means of levers or handwheels. The seals and the closing and opening arrangements for such doors and hatches must be so designed that, with each closing, a planned watertight state is reached even for the most difficult conditions. This gives rise to a whole series of drawbacks in the manufacture, assembly and use, such as, for example, a very large number of expensive mechanical elements, great weight, the requirement for short maintenance intervals, awkward manipulation, high manufacturing, assembling and incidental costs, as well as the requirement for the separate operation of each door or hatch without the possibility of remote control. These requirements and disadvantages are a high price to have to pay for typical prior art systems.
With standard doors and windows, or with doors for autoclaves, it is already known from German Laid Open Patent Application Nos. DE-OS 22 30 132, DE-OS 15 09 709, and DE-OS 15 09 716, to arrange, between the peripheral edge of the door and the frame, an elastic tube which can be so pressurized by connecting it to a pressure medium source that the gap between the inner periphery of the frame and the door leaf is bridged-over and thus provides a peripheral seal between the door and the frame. With one of these known solutions (DE-OS 15 09 716), this type of seal has already been used in addition to the mechanical locking of the door. The use of this known sealing principle for ship's doors and hatches would, as is the case with previously known mechanical sealing systems, make it necessary for the pressure seal to be pressure-relieved or pressurized again with each opening and closing operation. This is particularly disadvantageous with doors which must be very frequently opened and closed because, in such cases, the dynamic seals which must be preferably pnuematically or possibly hydraulically actuated are subjected to frequent stressing, quite apart from the not-inappreciable consumption of energy and waste of the time needed in pressurizing and depressurizing the seals.